Ohhh I have done this many times. (so much so that hubby now "expects" surprises on our trips)
First time we were traveling to UK, (which he knew) but I booked flights via USA so 1. we could see his favourite band "YES" play at San Francisco, then I had tickets to his football team - Green Bay, had tickets to home game. Then we got to London and did all the things he knew about.
On the way home, he thought we were coming straight back.... No.... detour via Las Vegas, where I had planned renewal of our Wedding Vows with Elvis, had even sent out wedding invites, and had the ceremony live streamed back to our friends. Then a few days in LA.
Next - Trip to USA, he knew nothing about it, other than I was looking at things for our next break. When he walked out of a meeting in Sydney, I handed him his passport and said - we are going now.... Then the 2 kids jumped out and said "we are coming too!! ) What they all did not know, was that I had booked via Shanghai, so when we got to the airport, I told them to find out which gate for flight MU561 - all 3 said "WHAT !! Shangahi !!! Yes, we are having a few days there before heading to USA.
Some times it is easier to plan surprises "while you are already away" While on anther trip to USA, booked helicopter trip out to Grand Canyon, he was wondering why I was in such a hurry to get back to our hotel - well I knew that the limo was waiting for us!
Best of luck with your plans. It can be done.